


What Goes Where

by Unforth



Category: Supernatural
Genre: Alternate Universe - Modern Setting, Bottom Dean Winchester, Come Eating, Come Inflation, Crack, Creature Castiel (Supernatural), Loss of Virginity, M/M, Monster Castiel (Supernatural), Overstimulation, Tentacle Sex, Top Castiel, Trope Subversion/Inversion, Twink Dean Winchester, Unrealistic Sex, tentacle sounding
Language: English
Status: In-Progress
Published: 2019-01-22
Updated: 2019-01-23
Packaged: 2019-10-14 12:32:31
Rating: Explicit
Warnings: Underage
Chapters: 4
Words: 1,861
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17508704
Author URL: https://archiveofourown.org/users/Unforth/pseuds/Unforth
Summary: Castiel is the shadow tentacle monster under the bed.Dean is the brand new owner of the bed.Castiel has *no idea* what he's doing.(Or: All your favorite out there tentacle sex kinks in one cracktastic fic...possibly more sex tags to be added, I haven't fully decided yet)





	1. Chapter 1

**Author's Note:**

> My son woke me up to early and I had this idea for a ridiculous cracky trope inversion monster Cas/underage Dean fic.
> 
> Dean is like 16 or 17, I don't even know.
> 
> Everything will be completely consensual.
> 
> I'll be writing this over the course of today as I have time, and maybe into tomorrow, depending how long it gets.
> 
> I have no idea what I'm doing.
> 
> (and don't worry, I ALSO wrote almost 1000 words of Thursday's Angel, this is just a mental vacay...)

So, like...Castiel is nervous. Really nervous. Life in a mattress store isn't glamorous, and there are always too many people and too much noise, but he'd gotten used to it, you know? And it's a simple existence. Customers come and go all day, lying down on his bed, poking it, prodding it, bouncing on it, occasionally - the eternal frustration of the employees - jumping on it, but no one sleeps there. Well, aside from that one time, but that was a fluke and the guy got kicked out of the store despite protesting it was an accident, he hadn't meant to sleep, but the bed was just so comfortable.

But being in the show room is nothing like being purchased and taken home, because there's no one there at night. No one to haunt. No one to frighten. No one to do...those things...that his parents had solemnly told him would be his responsibility to do once he had a human sleeping above him.

And now...Castiel ...well, Castiel's bed...sure they're a package deal but they're not actually synonmous...has been bought.

At the floor model discount, no less.

When Gabriel had been purchased, he'd been loaded into a truck, no guess where his new home would be, and Castiel hadn't heard anything from him since. Castiel had anticipated the same brusque, abrupt removal, but instead, a family came on his pick up day. He remembered them vaguely, a father who had looked at the mattress price tag, had nodded decisively, and had told the salesmen he'd buy that one without a single testing lie down.

Now, they came all four - the man, accompanied by a blonde woman and two teenagers, one tall and lean, the other still short and youth, with overgrown hair brushing into his eyes.

Working in amicable, comfortable tandem, the family lifted the mattress, the younger boy hopping down to disassemble the frame that had supported it. Harsh light fell on the usually safe shadows, and Castiel scrambled for darkness, seeping through the seaming to find sanctuary amidst the springs. He extended a tendril to the edges of the dark, to give him a glimpse of what lay beyond.

The teenager was staring at him. (Thank the darkness for the tutorial his parents had given him on the human lifecycle)

"This is my new bed?" grumbled the youth, his voice as gruff and deep as many adult males.

"It's...small. And all beat up."

Of course the youth wasn't looking at Castiel. He was looking at the bed. He couldn't possibly know that Castiel was there. That was the entire point, Castiel's presence was to be a mystery, a surprise, and he was to maintain that illusion as long possible, worming his way into the sleepers conscience, into his body, planting his seeds, preparing the ideal environment for himself, until his human had no freedom, no will, no choice but to submit.

That was what mom and dad had always said Castiel was supposed to do, anyway.

He couldn't deny...he didn't really like the sound of it.

"I'm not sleeping on that," grumbled the youth.

Maybe, if this fellow went on bed rebellion, Castiel wouldn't have to. That was a prospect to be optimistic about.

"Of course not, dear," the woman said idly.

Then again, if Castiel wasn't haunting a human, what would he even do with himself?

"You're such a jerk, Dean," the younger boy complained, high pitched and whiny. "You should be happy you're getting your own bed! I wish I was getting my own bed."

"It's all yours, Sammy," said Dean.(edited)

"Boys," barked the adult man. "Dean, you're getting this bed, and you're helping me carry it out to the truck. Now. And you bet your ass you're gonna sleep on it. You begged for it, you got it, end of story. And Sam, quit your bitching."

"Yeah, bitch," Dean smirked.

"Dean..."

Their apparent tiff gave way to baffling smiles as Dean took a position on one of the mattress, the adult took the other, and Sam and the woman together picked up the pieces of the bed frame.

Castiel had no idea what to make of their conflicting tones and bantering words.

He had a lot to learn about humans.

 


	2. Chapter 2

**Notes for the Chapter:**

> Whelp, my *intention* had been to update this throughout yesterday, but 30 minutes after I made the chapter 1 post we discovered a leak in the ceiling in our living room, and, well, now there's a giant hole in the room and no furniture and plans to remodel the whole thing and I didn't get any more writing done.  
> But we're back today! :)

Having someone sleep on Castiel's bed was...weird.

When people lay on the mattress briefly, that was one thing. Castiel could just ignore them. But Dean was just...there, asleep, shifting occasionally. Making small noises. Totally unaware that Castiel was lurking beneath the box spring.

There were things Castiel should do.

Mom and dad had taught him about his powers. Telepathy. Body shifting. Semen that modified the host environment to be more accommodating. The list went on.

Most of the powers had to do with sex.

Castiel had...mixed feelings about sex.

Yet, there he was. In a home. With a human. There were things he was supposed to do.

Sex things.

He understood the theory of coitus - mom and dad had diagrams they'd shown to all the children, with different images depending on whether the intended host was male or female - but the practice?

Dean was clear as day to Castiel in the midnight darkness. There was a blanket over him. He was wearing pajamas. His mouth was closed. All the places Castiel was supposed to enter were inaccessible.

And yeah, he could seep into Dean's dreams and keep him asleep, slip his darkness between the covers, slip a tendril between Dean's lips, wrap himself around Dean's legs and nudge them apart...

...but he didn't want to.

Dean looked so comfortable.

So Castiel sat.

And watched.

And tried, oh he tried, to psych himself up to act.

And slowly, slowly, the room went from black to gray.

Somewhere in the house, an alarm went off.

And Castiel slipped back beneath the bed, opportunity lost.

He'd do better tomorrow.

 


	3. Chapter 3

"Yo, Sammy! Off the bed!"

A week's cohabitation with the Winchesters passed surprisingly quickly.

"No, jerk! I like your bed. It's bouncy!"

The family was supremely different from Castiel's own.

"Quit being such a bitch! You're gonna fuck up the springs!"

Castiel's mother, Naomi, was authoritative, controlling, directive.

"Like you care about springs...you're just jealous that I'm getting away with jumping on the bed, and you're not."

Castiel's father, Ron, was...doofy.

"Boys! Neither of you is allowed to jump on the bed!"

Castiel's dozens of siblings ran the gambit from dead serious, like Uriel, to constant joker, like Gabriel.

"Yeah, Sam, neither of us is allowed to jump on the bed."

The family dynamic was complicated, the children joining in cliques, their parents training them for their mission, Ron occasionally doting on them.

"Dean, don't pretend to be your father."

The Winchester's...well, their father played the role that Castiel's mother usually took,  and the two brothers squabbled yet seemed quite fond of each other...when the other wasn't looking...and both their parents worked, and the boys did their homework, and their life followed very set patterns dictated by jobs and school instead of by the times the truck came to pick up new shipments.

"Alright, bed time boys!"

Though he'd only been there days, Castiel was already used to the rhythm. Now Sam would say...

"Come on, dad, ten more minutes!"

...and Mary would say...

"You heard your father! Bed time!"

...and Dean would say...

"Yeah, bitch, go to bed. Your bed. In your room. Leave me the fuck alone."

...and John would say...

"Watch your tongue, boy!"

...and everyone laughed, and Sam stumbled from Dean's room, and Dean closed and locked the door, and stripped...

...and Castiel observed.

And yearned.

And wondered what was holding him back from doing as he should.

"Brush your teeth!" Mary's muffled voice muttered through the door.

Dean shook his head, rolled his eyes, and flopped into bed.

"Whatever."

If only Castiel could talk to him.

If only Castiel could be part of a family like this one.


	4. Chapter 4

Watching Dean was...nice. Peaceful. Based on what Castiel knew of how his species operated, he'd assumed his nights would be frenetic with activity. And perhaps they would be, if Castiel initiated anything, but as long as he didn't, things were serene. Dean went through his days with the permanent hint of a smirk on his face, but when he slept, he relaxed, eased, into an appearance that Castiel found quite aesthetically pleasing. Theoretically, under the cloak of night, Castiel could explore and move about the house. Brightness was unpleasant, painful, dangerous if it was intense enough or sustained enough, but in the peace of midnight Castiel could go where he would. Even should John, on a midnight snack binge, flick a switch, there were perpetually enough shadows for Castiel to seek safety. Heck, he didn't even have to restrict his attentions to Dean. He could visit one of the other Winchesters, or, if he felt daring, leave the house and meet the neighbors.

Castiel could.

And, once, he had taken the grand tour of the small, pleasant suburban house.

But there was nothing nearly so interesting as Dean in any other room, or any other home, or any other place in the world, Castiel thought

Explaining Dean's appeal was complicated, but upon reflection, Castiel traced it to his affection for his brother Gabriel. They were a lot alike in some ways - and would probably hate each other - both tricksome, both intelligent, both deeply committed to their families, both determined to maintain the illusion that they weren't deeply committed to their families.

The day Gabriel had been shipped from the warehouse had been nearly as bad a wrench as Castiel's own departure, but with Dean, Castiel felt at home, comfortable, safe.

This was, perhaps, a strange attitude to maintain, given that Castiel was expected to breed the young man.

But, then, Castiel parents cherished and respected each other. Naomi had suggested such was an indulgence, a fluke, and not to be expected, but Castiel had dared hope that whoever he ended up with, he might forge a similar relationship.

To accomplish that, he'd have to reveal himself.

Or he could do as he aught, do as he was taught, and...get things going.

Neither felt right.

Neither even felt possible.

So instead, Castiel watched, night after night, week after week, lurking and thinking and convincing himself, maybe tomorrow night.

Until the night Dean seemed unusually restless.

Until the night Dean sat up, and Castiel froze, a mass of living darkness cloaked by the darkness of the room.

Until Dean appeared to look right at him, smirked, and said, "take a picture, it'll last you longer."

Oh, no!   
Cas bolted for the shadowed depths safe amidst the box spring, but he already knew it was too late.   
Some way, some how, Dean knew Castiel was there.   
"Aw, come on, don't be like that!"

Castiel didn't budge. Fear locked him into a static form, made the darkness seem dangerous.

Dean sighed. "...maybe I've been imagining shit after all."

And, eventually, mercifully, Dean went back to sleep.   
No more delays.   
Castiel had a job to do, and he'd better start doing it.   
Tomorrow night.

  
  


**Author's Note:**

> More to come...


End file.
